Hey mouse, just got back from the Plant & Animal Genome conference in lovely San Diego. Sorry to not look you up again... had meetings with clients the whole time.

yeah yeah yeah - you were just afraid to face my wrath BECAUSE YOU DARED TO DISAGREE WITH ME!!!!!!!

although to be precise, i really don't know if there are new variations arising in prions - that wasn't made clear (to me, at any rate) in the article. i think i said, in like my second post that if there were new variants, then yes, i would consider it evolution. but without a source of continuing variability yadda yadda yadda.

but now you have me curious, dro - do you consider a source of new variants necessary for evolution? or is the process of selection on a fixed pool of existing forms (however that pool arose) sufficient?_________________aka: neverscared!
a flux of vibrant matter

err, can we just go back to if new variants arise in prions? The article I read said that each time a prion induces a structural change in the normal protein, the structures can vary. Some structures are common, some rare. So that sounds like new variations to me.

Here's an example to get back to your question. Stickleback fish live in the ocean, and the population has a large amount of genetic variation. After the last Ice Age, when the glaciers pulled back, some stickleback got caught in lakes all over the world. In many of the lakes, stickleback lost their armor plating, changed mating behavior, color and many other attributes. These changes happened so quickly that they are not the result of new mutations in the population, but just selection on existing genetic variation. Is this evolution?

err, can we just go back to if new variants arise in prions? The article I read said that each time a prion induces a structural change in the normal protein, the structures can vary. Some structures are common, some rare. So that sounds like new variations to me.

Here's an example to get back to your question. Stickleback fish live in the ocean, and the population has a large amount of genetic variation. After the last Ice Age, when the glaciers pulled back, some stickleback got caught in lakes all over the world. In many of the lakes, stickleback lost their armor plating, changed mating behavior, color and many other attributes. These changes happened so quickly that they are not the result of new mutations in the population, but just selection on existing genetic variation. Is this evolution?

well, you've got me there. i was going to say, if you put them together and they can breed, it's not evolution - but then i realized you said 'changed mating behavior'. so even if, somehow, they got put back together, they are going to behave like separate species.

of course, i _could_ weasel out by pointing out that, although they might not have needed mutations to differentiate into distinct species, they are still going to have mutations occurring, so they can continue to change.....

i was thinking about things like dogs. dogs have clearly undergone substation selection (albeit not natural) - but they are still considered all one species.

i guess it gets down to the old taxonomist's dilemma - is morphology sufficient to determine a species, or do you have to throw it into a blender and get the dna comparisons?_________________aka: neverscared!
a flux of vibrant matter